In Sexy Librarian: File Under Rock Musical (Joking Envelope at the Minneapolis Theatre Garage through May 21) Sundberg plays Constance Black, ultra-frumpy librarian, frizzy-haired, near-sighted, bent under the weight of books, wearer of a long and formless woolen skirt. Constance finds a mysterious notebook containing a magic phrase. She utters the phrase (actually she sings it; all this happens in a song) and becomes… the Sexpot, slinky and bespangled. Black then rips into the play’s plot: her relationships with Chad the actor (with whom the luscious Sexpot has cosmic sex) and Frederick, her fellow librarian (who badly wants to have cosmic sex with Constance). The powers-that-be in the town of Dense Woods want to tear down the library and replace it with tree statues. Will Constance find her true self and stop them?

Sundberg makes the louche play work. As the Sexpot she is attractive and convincingly over-sexed but I came to greatly prefer her quiet and composed Librarian. Sundberg gives the frowzy Constance razor sharp cynicism and an impish grin. She makes long deliberate takes. The overall effect is, imho, very sexy.

Sundberg is greatly aided by her two male compatriots. As Frederick, Constance’s superior, arthritic hands permanently thrust into his pockets, Sam Landman displays edgy amiability and impeccable comic timing. When he suddenly (and for unclear reasons) recovers the use of his hands, Landman is a hoot and a half. As is Mike Rylander who plays Chad the actor (he’s auditioning for the timeless role of “Guy Selling Ladies Swimwear”) beautifully. He’s gorgeously air headed and appropriately swept off his feet by the hungry Constance. The rest of the ensemble (Kevin McLaughlin, Katie Kaufman, Lisa Bol and phillip andrew bennett) are quite good.

As to the material, well, gee. Joseph Scrimshaw (who also directs and plays the drums) has written a script that lurches along with admirable bravado and with regular flashes of brilliance (“You’re prettier, but meaner.” “Which is your Jekyll and which is your Hyde?”) But the plot is garbled, fitfully developed and repetitive. How many toilet paper jokes can one play sustain? Still, as is always the case with Joking Envelope, the material is played with seriousness and passion. This adds up to a recognizable style.

The music, composed by Mike Hallenbeck, provides good rock band energy (and features some soaring guitar playing by Adam Whisner). But the songs feel similar and they plod along without really driving the action. They become, essentially, interludes and this exacerbates a length problem.

Still, funny stuff here and the actors make Sexy Librarian worth a visit. Myself, I’m waiting for Ms. Sundberg to find material worthy of her immense talent. CTC’s recent Robin Hood gave us a taste of what she can do. She’s one of our best.